I do realize the use of app killers is generally not recommended with most versions of Android from 2.2 on up. However, as I'm not rooted, and was tired of the random reboots, I decided to resurrect one I used before. I'm currently using Advanced Task Killer Pro. I used this with my older LG Optimus V when it was running stock Froyo on the phone. It's been since reworked for Jelly Bean, so I decided to give this a try. So far, it's greatly reduced random reboots for me. I am careful to adjust it, so the app doesn't kill/force close system functions, or apps that I need to absolutely have running in the background. I have it set up in "Crazy" mode, which kills every app that is taking up memory, even ones that aren't directly running except for one that is actually in use. It seems to work well for me this way. I usually get back around 140-150 MB of system memory. I set the Auto Kill to free up memory every 30 minutes. That's more than enough time for some apps to partly come back on if needed before Auto Kill does its thing again. (At least it is on my phone.) I'm beginning to think that the random reboots are caused by having too many apps in the background that are tweaked to receive a lot of notifications. Perhaps if one has too many of these apps, I guess. I've tried consolidating some apps, like going from using facebook and twitter separately, to using hootsuite (which gets feeds from both sites and a few others). I've also eliminated some apps, like Chrome, which was too bloated and slow for me.